MEMS mirror with parallel springs and arched support for beams

ABSTRACT

A micro-electro-mechanical system (MEMS) mirror device includes (1) a mirror, (2) a first group of spring elements coupled to one half of the mirror, (3) a first beam coupled to the first group of spring elements, (4) a first spring coupled to the first beam, and (5) a first stationary pad coupled to the first spring. The device further includes (6) a second group of spring elements coupled in parallel to another half of the mirror, (7) a second beam coupled to the second group of spring elements, (8) a second spring coupled to the second beam, (9) and a second stationary pad coupled to the second spring. The device further includes a third beam that rigidly interconnects the first and the second beams so they rotate the mirror in unison.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.10/910,384, filed on Aug. 2, 2004, and U.S. patent application Ser. No.11/201,672, filed on Aug. 10, 2005, which are commonly assigned andincorporated herein by reference.

FIELD OF INVENTION

This invention relates to micro-electro-mechanical system (MEMS)devices, and more particularly to MEMS scanning mirrors.

DESCRIPTION OF RELATED ART

FIG. 1 illustrates a conventional MEMS mirror device 100. Device 100includes a mirror 102 having a first half connected rigidly to a rigidbeam 108. Beam 108 is then coupled by a torsion spring 110 to astationary pad 112. Mirror 102 has a second half connected rigidly to arigid beam 118. Beam 118 is then coupled by a torsion spring 120 tostationary pad 112. Although not shown, rotational comb teeth may extendfrom beams 108 and 118 to be interdigitated with stationary comb teeth.The rotational and stationary comb teeth form an actuator that rotatesmirror 102 along a rotational axis 122.

FIG. 2 illustrates a model of device 100 that illustrates the rotationof mirror 102 as linear oscillation. As they are rigidly connected,mirror 102 and beams 108 and 118 can be modeled as a single mass havingone degree of freedom. In other words, beams 108 and 118 oscillatemirror 102 in unison. Referring back to FIG. 1, the rotation angle ofmirror 102 is limited to the rotation angle of beams 108 and 118 eventhough a different (e.g., preferably greater) angle may be desired.Thus, what is needed is a MEMS mirror device that allows the mirror torotate at a different angle than the actuator.

SUMMARY

In one embodiment of the invention, a micro-electro-mechanical system(MEMS) mirror device includes (1) a mirror, (2) a first group of springelements coupled to one half of the mirror, (3) a first beam coupled tothe first group of spring elements, (4) a first spring coupled to thefirst beam, and (5) a first stationary pad coupled to the first spring.The device further includes (6) a second group of spring elementscoupled in parallel to another half of the mirror, (7) a second beamcoupled to the second group of spring elements, (8) a second springcoupled to the second beam, (9) and a second stationary pad coupled tothe second spring. The device further includes a third beam that rigidlyinterconnects the first and the second beams so they rotate the mirrorin unison.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate a conventional MEMS mirror device.

FIGS. 3 and 4 illustrate a MEMS mirror device in a prior commonlyassigned U.S. patent application.

FIGS. 5 and 6 illustrate a MEMS mirror device in one embodiment of theinvention.

FIG. 7 illustrates a MEMS mirror device in another embodiment of theinvention.

FIGS. 8A and 8B illustrate the MEMS mirror device of FIG. 7 with adifferent spring design in one embodiment of the invention.

FIGS. 9A and 9B illustrate the MEMS mirror device of FIG. 8A with adifferent spring design in one embodiment of the invention.

FIGS. 9C and 9D illustrate different spring designs in embodiments ofthe invention.

Use of the same reference numbers in different figures indicates similaror identical elements.

DETAILED DESCRIPTION OF THE INVENTION

Hereafter a spring is differentiated from a rigid beam by the amount ofstress they experience during rotation. During rotation, the springstores most of the potential/strain energy and the rigid beamexperiences very low stress compared to the spring.

FIG. 3 illustrates a micro-electro-mechanical system (MEMS) mirrordevice 300 as disclosed in U.S. patent application Ser. Nos. 10/910,384and 11/201,672. Device 300 includes a mirror 302 having a first halfcoupled by a torsion spring 304 to a rigid beam 308. Beam 308 is thencoupled by a torsion spring 310 to a stationary pad 312. Mirror 302 hasa second half coupled by a torsion spring 314 to a rigid beam 318. Beam318 is then coupled by a torsion spring 320 to stationary pad 312.Although not shown, rotational comb teeth may extend from beams 308 and318 to be interdigitated with stationary comb teeth. The rotational andstationary comb teeth form an actuator that rotates mirror 302 along arotational axis 322.

FIG. 4 illustrates a model of device 300 that illustrates the rotationof mirror 302 as linear oscillation. The oscillations of beams 308 and318 are transferred to mirror 302 by springs 304 and 314. Springs 304and 314 are intended to amplify the oscillations of beams 308 and 318 sothat mirror 302 oscillates at a greater magnitude than beams 308 and318. However, as beams 308 and 318 are coupled by springs at both ends,they have multiple degrees of freedom and may not oscillate in unison.When beams 308 and 318 do not oscillate in unison, they may work againsteach other and make it difficult to control the oscillating of mirror302. Furthermore, they may also generate unwanted mirror vibration inaddition to the mirror rotation about axis 322.

FIG. 5 illustrates a MEMS mirror device 500 in one embodiment of theinvention. Device 500 includes a mirror 502 having a first half coupledin parallel by torsion springs 504 and 506 to a rigid beam 508. Beam 508is then coupled by a torsion spring 510 to a stationary pad 512. Mirror502 has a second half coupled in parallel by torsion springs 514 and 516to a rigid beam 518. Beam 518 is then coupled by a torsion spring 520 tostationary pad 512. Beams 508 and 518 are interconnected rigidly by asupport beam 523 so beams 508 and 518 rotate in unison. In oneembodiment, support beam 523 is an arch extending from beams 508 and 518around mirror 502. Springs 504, 506, 510, 514, 516, and 520 are formedso their rotational axes align along a rotational axis 522 of mirror502. Although not shown, rotational comb teeth may extend from beams 508and 518 to be interdigitated with stationary comb teeth. The rotationaland stationary comb teeth form an actuator that rotates mirror 502 alongaxis 522.

FIG. 6 illustrates a model of device 500 that illustrates the rotationof mirror 502 as linear oscillation. As beams 508 and 518 are connectedrigidly by support beam structure 523, they have a single degree offreedom and oscillate in unison. As beams 508 and 518 oscillate inunison, the oscillation of mirror 502 is easy to control. Theoscillation of beams 508 and 518 is transferred to mirror 502 by springs504, 506, 514, and 516. Springs 504, 506, 514, and 516 in turn amplifythe oscillation of beams 508 and 518 so that mirror 502 oscillates at agreater magnitude than beams 508 and 518. As multiple springs couplebeams 508 and 518 to mirror 502, each of the springs can be made oflower spring constant to prolong the life of the springs.

FIG. 7 illustrates a MEMS mirror device 700 in one embodiment of theinvention. Device 700 includes a mirror 702 having a first half coupledin parallel by torsion springs 704 and 706 to a proximal end of a rigidbeam structure 708. In one embodiment, springs 704 and 706 are U-shapedsprings. In other embodiments, springs 704 and 706 may be straight orserpentine-shaped springs. The first end of spring 704 is connected to arigid tab 711 extending from mirror 702 while the first end of spring706 is connected directly to mirror 702. The second ends of springs 704and 706 are connected directly to beam structure 708.

A distal end of beam structure 708 is then coupled by a torsion spring710 to a stationary pad 712. Beam structure 708 is further coupled by atorsion spring 726 to a stationary pad 728, where both spring 726 andstationary pad 728 are located in an opening in beam structure 708. Inone embodiment, springs 710 and 726 are serpentine springs. In otherembodiments, springs 710 and 726 may be straight springs.

Mirror 702 has a second half coupled in parallel by torsion springs 714and 716 to a proximal end of a rigid beam structure 718. In oneembodiment, springs 714 and 716 are U-shaped springs. In otherembodiments, springs 714 and 716 may be straight or serpentine-shapedsprings. The first end of spring 714 is connected to a rigid tab 713extending from mirror 702 while the first end of spring 716 is connecteddirectly to mirror 702. The second ends of springs 714 and 716 areconnected directly to beam structure 718.

A distal end of beam structure 718 is then coupled by a torsion spring720 to stationary pad 712. Beam structure 718 is further coupled by atorsion spring 736 to a stationary pad 738, where both spring 736 andstationary pad 738 are located in an opening in beam structure 718. Inone embodiment, springs 720 and 736 are serpentine springs. In otherembodiments, springs 720 and 736 may be straight springs.

Beams 708 and 718 are interconnected rigidly by support beams 723 and724 so beams 708 and 718 rotate in unison. In one embodiment, supportbeam 723 is an arch extending from a first side of beams 708 and 718(e.g., above a rotational axis 722 of mirror 702) around mirror 702, andsupporting beam 724 is an arch extending from a second side of beams 708and 718 around mirror 702 (e.g., below rotational axis 722).

Springs 704, 706, 710, 726, 714, 716, 720, and 736 are formed so theirrotational axes are aligned along rotational axis 722 of mirror 702.Rotational comb teeth 709 extend from beams structure 708 whilerotational comb teeth 719 extend from beam structure 718. Rotationalcomb teeth 709 and 719 are interdigitated with stationary comb teeth 744extending from stationary pad 742 facing the first side of beams 708 and718. Rotational comb teeth 709 and 719 are further interdigitated withstationary comb teeth 748 extending from stationary pad 746 facing thesecond side of beams 708 and 718. The rotational and stationary combteeth form an actuator that rotates mirror 702 along axis 722.

Although each mirror half is shown to be connected by two springs to abeam structure, additional springs can be added to connect the mirrorhalf to the beam structure. Although each beam structure is shown to beconnected by two springs to two stationary pads, additional springs canbe added to connect the beam structure to additional stationary pads.

FIG. 8A illustrates a MEMS mirror device 800 in one embodiment of theinvention. Device 800 is similar to device 700 (FIG. 7) except for itssprings. Mirror 702 is coupled by springs 804 and 814 to rigid beamstructures 708 and 718, respectively. Beam structure 708 is coupled bysprings 810 and 826 to stationary pads 712 and 728, respectively.Similarly, beam structure 718 is coupled by springs 820 and 836 tostationary pads 721 and 738, respectively. Springs 804, 810, 826, 814,820, and 836 are formed so their rotational axes are aligned alongrotational axis 722 of mirror 702.

FIG. 8B illustrates a simplified view of spring 804 in one embodiment ofthe invention. Spring 804 includes multiple spring elements.Specifically, spring 804 includes a straight section 852 having a firstend connected to mirror 702 and a second end connected to first ends oftwo parallel U-shaped sections 854 and 856 on opposing sides of section852. Second ends of sections 854 and 856 are in turn connected to beamstructure 708. In other embodiments, U-shaped sections 854 and 856 arereplaced by straight or serpentine-shaped spring sections. Sections 854and 856 are made thinner than section 852 to match the stresses theyexperience under rotation. As can be seen, sections 852 and 854 togethermake a serpentine-shaped spring. Similarly, sections 852 and 856together make a serpentine-shaped spring. Thus, spring 804 is similar totwo parallel serpentine springs.

Spring 814 is made in the same shape and size as spring 804. In oneembodiment, springs 810, 826, 820, and 836 are made of the same shape asspring 804 but their sizes may be different. Furthermore, as shown inFIG. 8A, the first ends of their straight sections 852 are connected tostationary pads instead of a mirror.

FIG. 9A illustrates a MEMS mirror device 900 in one embodiment of theinvention. Device 900 is similar to device 800 except springs 804 and814 have been replaced by springs 904 and 914, respectively. Springs 904and 914 are similar to springs 804 and 814 except each has additionalU-sections on opposing sides of its additional straight section. Springs904, 810, 826, 914, 820, and 836 are formed so their rotational axes arealigned along rotational axis 722 of mirror 702.

FIG. 9B illustrates a simplified view of spring 904 in one embodiment ofthe invention. Spring 904 includes multiple spring elements.Specifically, spring 904 includes a straight section 952 having a firstend connected to mirror 702 and a second end connected to a first end ofa second straight section 953. Section 953 is made thinner than section952 to match the stresses they experience under rotation.

The second end of sections 952 is further connected to first ends of twoparallel U-shaped sections 954 and 956 on opposing sides of section 952.In other embodiments, U-shaped sections 954 and 956 may be replaced bystraight or serpentine-shaped spring sections as described later. Secondends of sections 954 and 956 are in turn connected to beam structure708. Sections 954 and 956 are made thinner than section 952 to match thestresses they experience under rotation. As can be seen, sections 952and 954 together make a serpentine-shaped spring. Similarly, sections952 and 956 together make a serpentine-shaped spring. Thus, this part ofspring 904 is similar to two parallel serpentine springs.

A second end of section 953 is connected to first ends of two parallelU-shaped sections 958 and 960 on opposing sides of section 953. In otherembodiments, U-shaped sections 958 and 960 may be replaced by straightor serpentine-shaped spring sections as described later. Second ends ofsections 958 and 960 are in turn connected to beam structure 708.Sections 958 and 960 are made thinner than section 953 to match thestresses they experience under rotation. As can be seen, sections 953and 958 together make a serpentine-shaped spring. Similarly, sections953 and 960 together make a serpentine-shaped spring. Thus, this part ofspring 904 is similar to two parallel serpentine springs, and togetherspring 904 has four parallel serpentine springs.

Spring 914 is made in the same shape and size as spring 904. Althoughsprings 904 and 914 are shown with two pairs of U-shaped sections,additional pairs of U-shaped sections can be added.

FIG. 9C illustrates a simplified view of a spring 904C that can replacespring 904 in one embodiment of the invention. Spring 904C is similar tospring 904 except that U-shaped sections 954 and 956 have been replacedby straight sections 954C and 956C that are connected to the second endof straight section 952. As can be seen, sections 952 and 954C togethermake a U-shaped spring. Similarly, sections 952 and 956C together make aU-shaped spring. Thus, this part of spring 904C is similar to twoparallel U-shaped springs.

FIG. 9D illustrates a simplified view of a spring 904D that can replacespring 904 in one embodiment of the invention. Spring 904D is similar tospring 904 except that U-shaped sections 954 and 956 have been replacedby serpentine sections 954D and 956D that are connected to the secondend of straight section 952. As can be seen, sections 952 and 954Dtogether make a longer serpentine spring. Similarly, sections 952 and956D together make a longer serpentine spring.

In the various devices described above, the natural frequency of thedevice can be adjusted by applying a steady voltage difference betweenthe rotational and stationary comb teeth. For example, the voltagesapplied to the rotational and stationary comb teeth may be steadyvoltages, including ground.

In the various devices described above, the mirror can be rotated byapplying an oscillating voltage difference between the rotational andthe stationary comb teeth. For example, a first voltage applied to therotational comb teeth may be an oscillating voltage while a secondvoltage applied to the stationary comb teeth may be a steady voltage, orvice versa. The steady voltage may be ground or have an offset used toadjust the natural frequency of the device.

Various other adaptations and combinations of features of theembodiments disclosed are within the scope of the invention. Numerousembodiments are encompassed by the following claims.

1. A micro-electro-mechanical system (MEMS) mirror device, comprising: amirror; a plurality of spring elements coupled to one half of themirror; a beam structure having (1) a proximal end coupled by theplurality of spring elements to said one half of the mirror and (2) adistal end extending away from said one half of the mirror; a springcoupled to the beam structure; a stationary pad coupled by the spring tothe beam structure, wherein the plurality of spring elements and thespring have rotational axes aligned to a rotational axis of the mirror;and wherein the plurality of spring elements is selected from the groupconsisting of: a first plurality of spring elements comprising: astraight section, wherein a first end of the straight section is coupledto said one half of the mirror; a plurality of spring sections, whereinfirst ends of the spring sections are coupled to a second end of thestraight section, and second ends of the spring sections are coupled tothe beam structure; wherein the spring sections are selected from thegroup consisting of straight-shaped springs, U-shaped springs, andserpentine-shaped springs; a second plurality of spring elementscomprising: a first straight section, wherein a first end of the firststraight section is coupled to said one half of the mirror; and aplurality of first springs, wherein first ends of the first springs arecoupled to a second end of the first straight section, and second endsof the first springs are coupled to the beam structure; a secondstraight section, wherein a first end of the second straight sectionextends from the second end of the first straight section; a pluralityof second springs, wherein first ends of the second springs are coupledto a second end of the second straight section, and second ends of thesecond springs are coupled to the beam structure; wherein the firstsprings and the second springs are selected from the group consisting ofstraight-shaped springs, U-shaped springs, and serpentine-shapedsprings.
 2. The MEMS mirror device of claim 1, further comprising:another plurality of spring elements coupled to another half of themirror; another beam structure having (1) a proximal end coupled by saidanother plurality of spring elements to said another half of the mirrorand (2) a distal end extending away from said another half of themirror; another spring coupled to said another beam structure; anotherstationary pad coupled by said another spring to said another beamstructure; a support beam structure rigidly coupled to the beamstructure and said another beam structure so they rotate the mirror inunison; wherein said another plurality of spring elements and saidanother spring have rotational axes aligned to the rotational axis ofthe mirror.
 3. The MEMS mirror device of claim 2, wherein the supportbeam structure comprises an arch extending from the beam structure andsaid another beam structure around the mirror.
 4. The MEMS mirror deviceof claim 2, further comprising: another support beam structure rigidlycoupled to the beam structure and said another beam structure.
 5. TheMEMS mirror device of claim 1, wherein the spring and the stationary padare located within the beam structure.
 6. The MEMS mirror device ofclaim 1, further comprising: a plurality of rotational teeth extendingfrom the beam structure; another stationary pad; and a plurality ofstationary teeth extending from said another stationary pad, wherein thestationary teeth are interdigitated with the rotational teeth.
 7. TheMEMS mirror device of claim 1, wherein the spring comprises: a straightsection, wherein a first end of the straight section is coupled to thestationary pad; a plurality of spring sections, wherein first ends ofthe spring sections are coupled to a second end of the straight section,and second ends of the spring sections are coupled to the beamstructure; and wherein the spring sections are selected from the groupconsisting of straight-shaped springs, U-shaped springs, andserpentine-shaped springs.
 8. A method for operating amicro-electro-mechanical system (MEMS) mirror device, comprising:coupling one half of a mirror to a plurality of spring elements;coupling a beam structure by the plurality of spring elements to saidone half of the mirror, the beam structure having (1) a proximal endcoupled to the plurality of spring elements and (2) a distal endextending away from said one half of the mirror; coupling the beamstructure to a spring, wherein the plurality of spring elements and thespring have rotational axes aligned to a rotational axis of the mirror;coupling a stationary pad by the spring to the beam structure; rotatingthe beam structure, wherein the plurality of spring elements transfer arotational motion of the beam structure to the mirror so the mirrorrotates at a different angle than the beam structure; and wherein theplurality of spring elements is selected from the group consisting of:first plurality of spring elements, comprising: a straight section,wherein a first end of the straight section is coupled to said one halfof the mirror; and a plurality of spring sections, first ends of thespring sections being coupled to a second end of the straight section,second ends of the spring sections being coupled to the beam structure,the spring sections being selected from the group consisting ofstraight-shaped springs, U-shaped springs, and serpentine-shapedsprings; a second plurality of spring elements, comprising: a firststraight section, wherein a first end of the first straight section iscoupled to said one half of the mirror; and a plurality of firstsprings, wherein first ends of the first springs are coupled to a secondend of the first straight section, and second ends of the first springsare coupled to the beam structure; a second straight section, wherein afirst end of the second straight section extends from the second end ofthe first straight section; a plurality of second springs, wherein firstends of the second springs are coupled to a second end of the secondstraight section, and second ends of the second springs are coupled tothe beam structure; wherein the first springs and the second springs areselected from the group consisting of straight-shaped springs, U-shapedsprings, and serpentine-shaped springs.
 9. The method of claim 8,wherein said rotating the beam structure comprises: providing a firstvoltage to a plurality of rotational teeth extending from the beamstructure; and providing a second voltage to a plurality of stationaryteeth, the stationary teeth being interdigitated with the rotationalteeth.
 10. The method of claim 8, further comprising: coupling anotherhalf of the mirror to another plurality of spring elements; couplinganother beam structure by said another plurality of spring elements tosaid another half of the mirror; coupling said another beam structure toanother spring, wherein said another plurality of spring elements andsaid another spring have rotational axes aligned with the rotationalaxis of the mirror; coupling another stationary pad by said anotherspring to said another beam structure; and rigidly coupling the beamstructure and said another beam structure with a support beam structureso they rotate the mirror in unison.
 11. The method of claim 8, whereinthe spring comprises: a straight section, wherein a first end of thestraight section is coupled to the stationary pad; a plurality of springsections, wherein first ends of the spring sections are coupled to asecond end of the straight section, and second ends of the springsections are coupled to the beam structure; and wherein the springsections are selected from the group consisting of straight-shapedsprings, U-shaped springs, and serpentine-shaped springs.
 12. Amicro-electro-mechanical system (MEMS) mirror device, comprising: amirror; a first spring coupled to a first half of the mirror; a firstbeam structure having (1) a proximal end coupled by the first spring tothe first half of the mirror and (2) a distal end extending away fromthe first half of the mirror; a second spring coupled to the first beamstructure; a first stationary pad coupled by the second spring to thefirst beam structure; a third spring coupled to a second half of themirror; a second beam structure having (1) a proximal end coupled by thethird spring to the second half of the mirror and (2) a distal endextending away from the second half of the mirror; a fourth springcoupled to the second beam structure; a second stationary pad coupled bythe fourth spring to the second beam structure; and a support beamstructure rigidly coupled to the first and the second beam structures sothey rotate the mirror in unison.
 13. The MEMS mirror device of claim12, wherein the support beam structure comprises an arch extending fromthe first and the second beam structures around the mirror.
 14. The MEMSmirror device of claim 12, further comprising: another support beamstructure rigidly coupled to the first and the second beam structures,wherein the support beam structure comprises an arch extending from afirst side of the first and the second beam structures around themirror, and said another support beam structure comprises a second archextending from a second side of the first and the second beam structuresaround the mirror.
 15. The MEMS mirror device of claim 12, wherein thesecond spring and the first stationary pad are located within the firstbeam structure.
 16. The MEMS mirror device of claim 12, furthercomprising: a plurality of rotational teeth extending from the first andthe second beam structures; a third stationary pad; and a plurality ofstationary teeth extending from the third stationary pad, wherein thestationary teeth are interdigitated with the rotational teeth.
 17. TheMEMS mirror device of claim 12, further comprising: a fifth springcoupled to the first half of the mirror and the first beam structure;and a sixth spring coupled to the second half of the mirror and thesecond beam structure, wherein the first, the third, the fifth, and thesixth springs comprise U-shaped springs having rotational axes alignedto a rotational axis of the mirror.
 18. The MEMS mirror device of claim12, wherein the first and the third springs are each selected from thegroup consisting of: a first plurality of spring elements, comprising: astraight section, wherein a first end of the straight section is coupledto a respective half of the mirror; a plurality of spring sections,wherein first ends of the spring sections are coupled to a second end ofthe straight section, and second ends of the spring sections are coupledto a respective beam structure; wherein the spring sections are selectedfrom the group consisting of straight-shaped springs, U-shaped springs,and serpentine-shaped springs; a second plurality of spring elements,comprising: a first straight section, wherein a first end of the firststraight section is coupled to a respective half of the mirror; and aplurality of first springs, wherein first ends of the first springs arecoupled to a second end of the first straight section, and second endsof the first springs are coupled to a respective beam structure; asecond straight section, wherein a first end of the second straightsection extends from the second end of the first straight section; aplurality of second springs, wherein first ends of the second springsare coupled to a second end of the second straight section, and secondends of the second springs are coupled to the respective beam structure;wherein the first springs and the second springs are selected from thegroup consisting of straight-shaped springs, U-shaped springs, andserpentine-shaped springs.
 19. A method for operating amicro-electro-mechanical system (MEMS) mirror device, comprising:coupling a first half of a mirror to a first spring; coupling a firstbeam structure by the first spring to the first half of the mirror, thefirst beam structure having (1) a proximal end coupled to the firstspring and (2) a distal end extending away from the first half of themirror; coupling the first beam structure to a second spring; coupling afirst stationary pad by the second spring to the first beam structure;coupling a second half of a mirror to a third spring; coupling a secondbeam structure by the third spring to the second half of the mirror, thesecond beam structure having (1) a proximal end coupled to the thirdspring and (2) a distal end extending away from the second half of themirror; coupling the second beam structure to a fourth spring; couplinga second stationary pad by the fourth spring to the second beamstructure; rigidly coupling the first and the second beam structureswith a third beam structure so the first and the second beam structuresrotate the mirror in unison; and rotating the first and the second beamstructures, wherein the first and the third springs transfer arotational motion of the first and the second beam structures to themirror so the mirror rotates at a different angle than the first and thesecond beam structures.
 20. The method of claim 19, further comprising:coupling a fifth spring to the first half of the mirror and the firstbeam structure; and coupling a sixth spring to the second half of themirror and the second beam structure, wherein the first, the third, thefifth, and the sixth springs comprises U-shaped springs havingrotational axes aligned to a rotational axis of the mirror.
 21. Themethod of claim 19, wherein the first and the third springs are eachselected from the group consisting of: a first plurality of springelements, comprising: a straight section, wherein a first end of thestraight section is coupled to a respective half of the mirror; aplurality of spring sections, wherein first ends of the spring sectionsare coupled to a second end of the straight section, and second ends ofthe spring sections are coupled to a respective beam structure; whereinthe spring sections are selected from the group consisting ofstraight-shaped springs, U-shaped springs, and serpentine-shapedsprings; a second plurality of spring elements, comprising: a firststraight section, wherein a first end of the first straight section iscoupled to a respective half of the mirror; and a plurality of firstsprings, wherein first ends of the first springs are coupled to a secondend of the first straight section, and second ends of the first springsare coupled to a respective beam structure; a second straight section,wherein a first end of the second straight section extends from thesecond end of the first straight section; a plurality of second springs,wherein first ends of the second springs sections are coupled to asecond end of the second straight section, and second ends of the secondsprings are coupled to the respective beam structure; wherein the firstsprings and the second springs are selected from the group consisting ofstraight-shaped springs, U-shaped springs, and serpentine-shapedsprings.
 22. The method of claim 19, wherein said rotating the first andthe second beam structures comprises: providing a first voltage to aplurality of rotational teeth extending from the first and the secondbeam structures; and providing a second voltage to a plurality ofstationary teeth, the stationary teeth being interdigitated with therotational teeth.